The present invention relates to a coupling device for a prosthesis, and more particularly to a flexible coupling that floats relative to the bone of an amputated limb so as to minimize disturbing the skin seal around the sleeve forming part of the socket.
Artificial limbs, or prothesis, have been used by amputees for many centuries. At first the prothesis were crude, shaped as sticks attached to legs or as hooks attached to arms. Recently, they have become more sophisticated, incorporating electronic equipment and servo motors to produce more natural limb movement. With all this development, however, problems still remain in means of attaching the prosthesis. When porothesis are worn for a long time, the harness and clamps create discomforting pressures.
Attempts have been made to minimize these problems, and one example such an attempt is disclosed in U.S. Pat. No. 3,947,897. In that particular device, a quick disconnecting lock pin is attached to the prosthesis and a socket is inserted within the intermedullary cavity of the bone for receiving such a pin. Interposed between the end of the socket and the skin is a sleeve constructed of bio-compatible material which provides compatibility between the implanted socket and the skin line which, in turn, heals therearound.
One problem with such a device is that the sleeve is fixed relative to the socket and stresses that are produced as a result of changes in the stump shape tend to cause the skin seal around the carbon sleeve to be disturbed.